Electromagnetic object-tracking-anddestroying method and system



2,769,9 75 ING R. H. RINES ELECTROMAGNETIC OBJECT-TRACKING -AND-DESTROYNov. 6, 1 956 y K METHOD AND SYSTEM Filed Oct. 29, 1945 5 Sheets-Sheet 1www Nov. 6, 1956 2 769,975

YR. H. RINES x ELECTROMAGNETIC OBJECT-(TRACKING-AND-DESTROYING METHODAND SYSTEM Filed Oct. 29, 1945 5 Sheets-Sheet 2 w82 l mi #Fa g IoFMuLT/v/B/wrof? M e @Z5/My Nov. 6, 1956 R. H. RINEs 2,769,975

ELECTROMAGNETIC OBJECT-TRACKING-AND-DESTROYING METHOD AND SYSTEM FiledOct. 29, 1945 5 Sheets-Sheet 3 OUTPUT OF V/.DEO AMF @MSHA/74H75? F76.6.)

r u W o W c m y M E D 2,769,975 ING Nov. 6, 1956 R. H. RINESELECTROMAGNETIC OBJECT-TRACKING-AND-DESTROY METHOD AND SYSTEM 5Sheets-Sheet 4 Filed Oct. 29, 1945 ll--I Nov. 6, 1956 R. H. RlNEs2,769,975

ELECTROMAGNETIC 0BJECT-TRACKING-AND-DESTROYING METHOD AND SYSTEM FiledOct. 29, 1945 5 Sheets-Sheet 5 V/JEO OU TPU T Ml/L 7'/ V/ERKITOR GAT/N6OUTPUT United Stats ELECTROMAGNETIC OBJECT-TRACKING-AND- DESTROYINGMETHQD AND SYSTEM The present invention relates to electric methods andsystems, and more particularly to methods and systems for controllingthe explosion of shells or other projectile explosives.

An object of the invention is to provide a new and improvedradio-locator=andtracking system.

A further object is to provide a novel radio-controlled tiring system.

A further object is to provide for controlling the burst of a shell orother projectile explosive from a point distant from the position of theprojectile in motion.

.According to present-day techniques, after a projectile, such as ashell or a rocket, has been red from a projector toward a target object,such as an airplane, the time of its explosion is controlled at theprojectile itself. The explosion may, for example, be under the controlof a time fuse, a powder-train fuse, a radio-transmitting-and-recevingmechanism, or a photocell fuse in the projectile. The control is such asto assure the explosion of the projectile at the moment of its approachtoward the airplane object. If a time fuse or a powder fuse be employed,the target airplane is detected, its line of ight is plotted in order tomake possible the prediction of its future position, and the timemechanism -in the projectile fuse is set accordingly before tiring. Inthe case of a radio fuse r a photocell fuse, the explosion of theprojectile is effected by the mere fact of its proximity to the targetobject, and no further control from the ground is necessary. All theseprior-art methods are subject to the disadvantage that the projectilemay explode at a time or a place where it will not harm the enemy andmay, in fact, damage a friend. At the very least, a premature or atoo-late or otherwise useless projectile explosion may serve to informan enemy aircraft that it is under fire. In the case of proximity fuses,furthermore, tiring at low-flying aircraft in low quadrants ofelevation, for example, will often cause premature explosion because ofthe proximity of the ground to the shell.

Another object of the present invention, therefore, is to explodevonlythose projectiles that are sufiiciently near to the airplane or otherenemy object to produce lethal effects.

Still another object is to prevent the explosion of projectiles thathave traveled beyond, or have otherwise missed, their mark.

A further object still is to provide a fuse mechanism for exploding theprojectile accurateiy, at any desired time during its ighL'from thepoint of its tiring, or from any other position remote from theprojectile.

Other and further objects will be explained hereinafter, and will beparticularly pointed out in the appended claims.

'The invention wiil now be more fully explained in connection with theaccompanying drawings, in which Fig. l is a diagrammatic view ofcircuits and apparatus arranged and constructed f according to apreferred embodiment thereof; Fig. 2 is a diagrammatic view showing aradioreceiving fuse provided' in the projectile, and operable in arentFatented Nov. f8, T356 conjunction with the circuits of Fig. 1 to causethe projectile to explode; Figs. 3 to 13, inclusive, represent idealizedvoltage-wave forms illustrating the operation of the various componentsof the disclosed circuits, Fig. 3 illustrating the transmittedradio-frequency pulses, Fig. 4 the output of the attenuator-rectier,Fig. 5 the output of the radio receiver, Fig. 6 the output of the videostages, Fig. 7 the brightening-pulse output of the multivibrator, Fig. 8the gate-pulse output of the multivibrator, Fig. 9 the output of thevideo amplifier at an instant after that corresponding to Fig. 6, Fig.10 the output of the delay circuit, Fig. 11 the sweep voltage producedbetween the horizontally spaced vertically disposed deiiector plates ofthc cathode-ray tube, Fig. l2 the radio-frequency trigger pulse, andFig. 13 the output of the ringing circuit; Figs. 14 and 15 are views ofthe cathode-ray-tube display, iilustrating the sweep, the echoes andother features; Fig. i6 is a diagrammatic view of circuits and apparatusfor providing a modified method of operation, to provide for J tiringany projectile at any position Within the lethal range, or at any timewhen the projectile occupies such position; Fig. 17 is a diagrammaticview of circuits and apparatus as adapted to operation with sound ofsupersonic energy, illustrating the dropping of a depth bomb upon asubmarine; Fig. 18 is a diagrammatic view illustrating a preferred typeof radio-frequency transmitter; Fig. 19 is a similar View of a delayline, such as may be embodied in the system of Fig. 1; and Fig. 2O is adiagrammatic view illustrating a preferred type of variablephasemultivibrator.

Any well known ultra-high-frequency radio-locator pulse transmitter mayne employed. A preferred type is illustrated in Fig. 18. Twotransmitting triodes 138 and ist@ are connected in parallel, with theircathodes 142 and 144 connected together through a grounded tunedradiofrequency circuit 146. This tuned circuit may assume any desiredform, such as a Lecher line or a tuned cavity (not Sho-wn). The anodes148 and 150 of the tubes 138 and itiare shown connected together througha tuned circuit comprising a condenser 152 and a coil 154, connected inparallel. The control-grid electrodes 156 and 15d of the tubes 138 and140 are connected together, through a condenser 160, kto a ground 162;and also, through a resister 164, to a grounded plate-supply battery166. As the condenser 160 is thus connected in parallel mid-point of theplate picked up by the con 16s of the therefore, travels, b y way of the..Engineering, by Terman.

conductors 134, to the antenna dipole 3, appearing as the saidtransmitted radio-frequency pulse 126, say, of 50 centimeterswavelength.

The dipole antenna 3 is illustrated in Fig. 1 as positioned at ythefocus of a parabolic or other directive reflector 6. A parasiticreflector 5 may be employed to refiect'the radiation emitted from thedipole 3 back on to the parabolic reflector 6. The parabolic reflector 6will then direct the energy out towards a target object, such as anairplane 7, and toward a shell or other projectile object 9 that hasbeen fired from a gun (not shown).

Upon reaching the objects 7 and 9, the radio pulses thus propagatedtowards these objects will become scattered and reflected back towardthe parabolic reflector 6 and the dipole 3, to be transmitted, by theconductors 134 and conductors 102, to a radio-frequency-receiveramplifier 11. The received radio-energy shell and target echoes arerepresented by Fig. 5 as a brief series of radiofrequency oscillations124 and 128, respectively, between similarly indicated received pulses123 picked up directly from the oscillatory transmitted pulses 126 (Fig.3). The amplifier 11 receives and amplifies these reflected andscattered radio echoes. The energy received by the amplifier 11 may thenbe detected in a detector 111 to produce direct-current pulses, and thenamplified in a video amplifier 130, in well known television fashion.Suitable apparatus for performing this function may be found described,for example, on page 749 of Radio Engineering, by F. E. Terman, 1937edition. Any well known superheterodyne system may also be used as areceiver, such as is described in Superheterodyne Reception ofMicro-Rays, Reeves and Ullrich, Electrical Communications, vol. 16, No.2, 1937.

The radio-locator transmitter 1, as shown diagrammatically in Fig. l, isconnected by conductors 45 and 174 to an.attenuator-and-rectifier 13,the details of which may be as illustrated in Fig. 18. A center tap 170of the coil 168 is there shown connected to the grounded side of theattenuator 176 by the conductor 45, Vshown grounded. The other side ofthe attenuator 17 6 is shown connected by the conductor 174 to one ofthe terminals of the coil 168. The said one terminal of the coil 168 isshown connected to one side of a rectifier 172 through one side of theattenuator 176. The other side of the rectifier 172 is shown connected,through a radio-frequency-choke coil 178, to the'non-grounded outputconductor 136, and a load resistor 180 is connected across the outputconductors 136.

The radio energy picked up by the coil 168, therefore, travels not onlyby way of the conductors 134 to energize the dipole antenna 3, but also,by way of the conductors 45 and 174, to the attenuator-and-rectifier 13.After passing through the attenuator 176 and the rectifier 172, andthrough the radio-frequency-choke 178, this energy appears asdirect-current Vpulses across the resistor 180. The pulse 182 (Fig. 4)represents that part of the radioenergy pulse that is attenuated andrectified in the attenuator-and-rectier 13. The pulse 182 will obviouslytake place at the same instant that the pulse transmitter 1 energizesthe antenna 3 to emit theradio-frequency pulse 126, and it is used totrigger the sweep generator The attenuator-and-rectifier 13 is connectedto a horizontal-sweep-generator circuit 15 by conductors 136,' shown inFig. 18 connected across -the terminals of the -resistor 180. Thegenerator 15 may, "for example, be of any conventional linear ornon-linear type, such, for example, as is illustrated on'page740 of thesaid Radio This produces a linear or nonlinear horizontal-sweep timebase between the horizontally spaced, vertically disposed deliectorplates 17 and electron stream horizontally. The saw-tooth-sweepvoltagethus produced between the plates 17 and V19 is 19 of a cathode-rayoscilloscope 21 for deflecting the 'j represented at 62 by Fig. 11. Theplate 19 is shown grounded. The video circuits are shown connected tothe vetrically spaced horizontally disposed deector plates 23, 25 byconductors 104 and 10S, respectively.

The same trigger voltage from the attenuator-and-rectifier 13 thattriggers the horizontal-sweep generator 15 may trigger also avariable-phase oscillator or strobegenerator, such as a multivibrator29, to produce pulse outputs in any desired phase relationship to thestart of the sweep 62 (Fig. 1l). This may be effected by connecting theattenuator-and-rectifier 13 to the multivibrator 29 by conductors 137.

The variable-phase multivibrator 29 may, for example, be of the typeshown in Fig. 20, where tubes 300 and 301 are shown respectivelyprovided with cathodes 306 and 307, control-grid electrodes 304 and 305,anode plates 302 and 303, and plate-load resistors Rp and Rp. A variablecoupling condenser C and a variable resistor R are connected in seriesto constitute a coupling circuit C-R from the plate circuit of the tube300 to the grid or input circuit of the tube 301, -the grid 305 of thetube 301 being connected to the junction between the `coupling condenserC and the resistor R. The grid 304 of the tube 300 is similarlyconnected to 'the junction between the variable coupling condenser C andthe variable resistor R', coupling the output circuit of the tube 301 tothe input circuit of Ithe tube 300. The condenserC may be charged from abattery 309 through `the resistor R and the plate resistor Rp. Thecondenser C' may be similarly charged from the battery 309 through theresistor R and the plate resistor Rp.

Let it be assumed that the tube 300 is jus-t cut off. A positive triggerpulse 182 (Fig. 4) is applied .to the grid 304 of the tube 300, causingthe tube to burst into conduction.v The voltage at the plate 302 of thetube 300 drops, and the voltage at 'the grid 305 of the tube 301 dropsalso, since it is coupled to the plate 302 by the condenser C. The tube301, therefore, cuts off, because of the negative voltage on the grid305. The voltage of the plate 303 of the tube 301 rises, and causes thegrid 304 of the tube 300 to rise further, thus increasing the conductionof the tube 300. When no further voltage' change occurs at the plate302, the condenser C becomes chargedpositively through the resistors Rand Rp from the plate-supply battery 309, until the voltage of the grid305 rises enough, depending upon the values of C and R, to c-ause thetube301'to conduct and cut off the tube 300. This point is reached atthe leading `or left-hand edge ofthe pulse 40 of Fig. 7. When no furtherchanges in vol-tage occur at the plate 303, the condenser C- chargesthrough -the resistor R', the Vsupply battery 309, and the plate loadRp', to restore the grid 304 of the tube 300 to its initial near cut-offcondition, The circuit then remains with the tube 301 partiallyconducting until the next trigger pulse 182 causes the tube 300 heavilyto con! Y duct again. The ktime that the process of restoring the grid304 to-its initial condition consumes is determinedV by the settings ofthe condenser C and-the resistor-R', and it is this phenomenon thatproducesthe desired multivibrator-pulse-outputs'. While-the `waveform 40is illustrated as a rectangularV pulse, this is, of course, idealized;

being, in actual practice, an exponentially dipping spike,

as is well known.

' VA negative pulse 40, Fig.v 7, thus appears' at the plate 303 and -apositive pulse 42, Fig. 8,V at the plate 302 of.V

lthe tube 300. Thewidth of these pulses is controllable,

asV above explained, by the condenser-resistor control Y The time atwhich these pulses occur, selected and controlled, as above explained,by the phase control -C-R, is shown in Fig. 7Va's occurring at anydesireddistance Ra'along the sweep.A Y l The .pulse 40 (Fig. 7) .is fedby conductors 103 between the cathode -60 and the control-gridelectrodeV 61 of the cathode-ray oscilloscope 21. Normally, theelectrode 61 vis biased negatively with respect to ythe cathode Theleft-hand edge 60 by, say, a battery 121, to allow a certain intensityof the electron stream to reach the oscilloscope face 27. A B-battery119 constitutes a source of supply between the cathode 60 and the anode125 When the brightening pulses arrive between the grid 61 and thecathode 60, the cathode 60 is rendered negative with respect to the grid61, whereupon the electrons emitted from the cathode 60 are permitted tobe accelerated, in the form of an increased stream, past the controlgrid 61 and Ithe anode 125 of the oscilloscope 21, to impinge finally onthe persistent uorescent oscilloscope face 27, brightening that part ofthe sweep starting with a point corresponding to the distance R3 fromthe s-tart of the sweep, and brightening a predetermined portion of thesweep of length corresponding to the width of the pulse 40.

After rectification, and preferably also amplification, in thedetector-and-video amplier stages 111 and 130, the received directpulses appear as shown as 63, and the echoes from the shell 9 and theaircraft 7 as shown at 4 and 8, respectively, in Fig. 6. The detectedand amplitied video signals are represented by Fig. 6 as they appear atthe instant that they are applied to the vertically spaced horizontallydisposed deector plates 23 and 25 to deflect Ithe sweep vertically, asshown in Figs. 14 and 15. The deflection 4, rep-resenting the echo fromthe shell 9, and the deflection S, representing the echo from theaircraft target 7, are shown in Figs. 14 and 15, together with the sweep2. In these two Figs. 14 and 15, the brightening pulse 40 of Fig. 7 isshown brightening the part 141 of the sweep associated with the echo 8.

A horizontal-sweep time base 2, the time constant of which depends onthe range to be covered, is thus produced on the iluorescent screen 27of the cathode-ray tube 21, with vertical deections corresponding, indistance from the start of the time base, to the distances from theantenna 3 of the objects 7 and 9 from which the radio waves arereflected or scattered. In accordance with well known radio-locationtechnique, the radio echo of the shell 9 will be shown at a range R1from the station and that of the object 7 at a range R2.

Since the control electrode 61 is biased negatively with respect to thecathode 60, however, this horizontal sweep will not be very bright onthe oscilloscope face 27. At such times as the brightening pulse 40 isapplied to the cathode 60 and the grid 61, by way of the conductors 103,from the multivibrator 29, the cathode 60 becomes negative with respectto the control-grid electrode 61. The effect of the said pulse,therefore, as previously described, is to brighten the sweep during theduration of the pulse 40.

When an operator has detected a target appearing as a 'deflection 8(Figs. 14 and 15), he may adjust the variable-phase multivibrator 29 tobring the edge of the on to the deflection 8, leaving, therebrighteningsection fore, a selected predetermined portion of the sweep brightenedbefore thel deflection 8, as shown at 141. ofthe portion 141 representsa future position of theprojectile which is traveling towards thetarget. By suitable design of the time constants or" the multivibrator29, this brightened portion 141 may be 1 made to correspond in width orrange to the lethal distance or range of the projectile. As previouslyexplained, the constants C- of Fig. 20 control the width of the pulse 40and, therefore, the width of the brightened section 141. 1f the lethalarea of the projectile is 170 yards, for example, the product cf thevalues of the capacitance C andthe resistance R' may `be adjusted toproduce a time constant of `approximately one microsecond. As shown inFigs.. 6 and 14, the echo 4 from ythe object 9 has Lnot yet reached itsselected future position and Vhas not yet entered the lethal area,shown'as i the horizontal region 141. Any explosion of the projectilewould therefore be ineffective at this time.

The instant that the projectile enters within the lethal distance orrange, its echo will enter the brightened sec-` tion 141, as shown byFigs. 9 and 15. should be exploded at this time. The method of explodingthe projectile at such a time will now be explained.

The gate-pulse output 42 of the multivibrator 29, as shown in Fig. 8,taken, for example, from the plate circuit of the first tube 300 of themultivibrator by the conductors 101, may be fed between the screen grid10 and the cathode 12 of a gating tube 14. Because of the properties ofmultivibrators, as previously explained, the timing and the pulse widthof the output 42 will be identical with the timing and the pulse widthof the output 40, taken from the second tube 301 of the multivibrator,though the pulse 42 is positive as compared with the negative pulse 40.The screen grid 10 may be biased by the battery 16, so as to prevent thetube 14 from conducting except during the application of the positivevariable-phase gating pulse 42.

The video output of the receiver, as shown in Fig. 6, may be fed by theconductors 104, 106 and 105, 107 between the control electrode 18 andthe cathode 12 of the gating tube 14 to cause the tube 14 to tend toconduct only during the application of the video pulses, such as thepulses 4 and S. The same video output shown in Fig. 6 may be fed by theconductors 104, 106, 110 and 105, 107, 109 to a delay circuit 20 of anyconvenient and well known type, such as an artificial transmission line,a time-constant circuit, or supersonic cell S9, Fig. 19. From the delaycircuit, the video output is fed, by conductors 112 and 113 (Fig. l),between a suppressor electrode 22 and the cathode 12 of the gating tube14. The suppressor electrode 22 is shown negatively biased by a battery114. The delay mechanism 20 should be adjusted to delay any videosignals by an amount of time corresponding to the pulse width of thegating pulse 42, that is, to the lethal range of the burst of theprojectile 9. For example, a supersonic cell 59 may be used, as shown inFig. 19, of material and length such that the video signals, fed to anexciter at one end, such as a piezo-electric crystal 57, and propagatedthrough the cell 59, shall be delayed by a length of time correspendingto the pulse width of the pulse 42, and then sent to the suppressorelectrode 22 by a receiver piezoelectric crystal SS at therother end ofthe cell 59. The echo 4 from the projectile 9 and the echo 3 from theobject 7, as shown in Fig. 10, will therefore arrive at the suppressorelectrode 22 of the gating tube 14 after a period of time displaced fromtheir respective positions in Fig. l0 by approximately the duration ofthe variablephase pulse output 40 or 42.

In Fig. 10, for illustrative purposes, the echo 4 from the shell 9 isindicated as arriving at the suppressor grid 22 at the same time thatthe echo 8 from the object 7, as shown in Fig. 9, arrives at the controlgrid 18 of the gating tube 14, and also during the continued applicationof the gating pulse 42 from the multivibrator, as shown in Fig. 8, atthe screen grid 10 of the gating tube 14.

At approximately the instant of time that the shell 9 enters the lethalarea, therefore, the gating tube 14 is opened up by the application ofthe gating pulse 42 to the screen grid 10, the object pulse 8 to thecontrol grid 18, and the delayed pulse 4 to the suppressor grid 22. Theactual instant is somewhat later, after a time correspondingapproximately to the width or the variablephase pulse 40 or 42. At thatinstant of time, the gating tube 14 conducts heavily, thus causing lesscurrent to flow through a relay coil 24 (Fig. 1) that is connected, Abyconductors 115, in parallel with the plate or output circuit of thegating tube 14. This diminution of current through the relay coil 24results in the closing of a relay switch 26, disposed in the plate oroutput supply of a radio-frequency trigger transmitter 28. Thetransmitter 2S is connected, by conductors 116,`to energize a furtherdipole antenna system 30, shown'as a directional system moving togetheror in synchronism with the reflector 6.

The projectile The transmitter 28, which is normally ineffective totransmit a signal, will thus be rendered effective to send a further andspecial directional radio signal 46 by way of the antenna system 30, ofa different frequency, for example, than the frequency of thetransmitter 1, as illustrated by Fig. 12, toward the projectile 9, toexplode the projectile.

A receiving-mechanism fuse provided in the shellprojectile 9 willtherefore cause the projectile 9 to explode almost immediately. Thisreceiving mechanism may comprise a receiving antenna or antennas. Twodipoles of dimensions resonant to the trigger-signal frequency are shown`at 31 and 64, preferably mounted externally to the fuse 55, as shown inFig. 2. The antenna or antennas feed into the fuse to energize alighttransparent radio-frequency cavity resonator 33 of dimensionsresonant to the radio waves transmitted by the trigger transmitter 28(Fig. 1). The radio-frequency resonant cavity 33 may, for example, beconstituted of polystyrene or any other similar light-transparentmaterial that serves as a conductor of high-frequency waves. Theresonator may be lled with an illuminating agent; for example, the raregas neon.

The antennas 31 and 64 are shown connected to the resonant cavity 33 bycoaxial lines 47 and 48, respectively. The radio-frequency energy thusfed into the gas in the cavity resonator 33 results in ionizing the gastherein, which therefore becomes illuminated. The illumination may befocused by a lens 35 upon a photocell 37, connected in series with asource of voltage, such as a battery 49 and an igniting mechanism 39,such as a charge, as of powder, for exploding the explosive mixture ofthe shell or the projectile. When the trigger transmitter 28 sends aradio signal that is received by the antennas and energizes the cavity33, therefore, the light from the ionization of the cavity resonatorcauses current to flow in the light-sensitive circuit of the photocell37, upon which the light is focused, thereby causing aV suiciently largecurrent to flow through the charge 39 to ignite the charge 39 and toexplode the shell.

If desired, the light-transparent radio-cavity resonator 33 may bemaintained periodically ionized by a striking potential from an energysource 50, as shown in Fig. 2. When the radio energy from vthe triggertransmitter 28 is conveyed into the cavity resonator, the gas willbecome further ionized, producing an increased intensity of lightdischarges and a greater current in the photo'cell circuit for settingoff the mechanism 39. Y

To prevent premature operation, thereby further to control the explosionof the projectile at any desired time, or when it occupies any desiredposition, from any desired remote point, an arming device, such as anarming propeller screw 41, may be provided to maintain the photocellcircuit open, by holding down a switch 43, for example, until such timeas the projectile has travelled a desired length of time. At the end ofthis time, the arming propeller 41 will have unscrewed itself from theVfuse nose in ight, thereby releasing the switch 43, and completing thephotocell circuit in the fuse for' operation upon the receipt of theenergizing radio-trigger signal from the remote point. Y

It may be desired to insure that the shell 9 shall re at any given timeafter it shall get within lethal range, or y when it occupies anydesired position within Vthe lethal range. SuchV an occasion mayY arise,for example, in the event that the radio-locator antenna system, 6should happen notl to pick up the signal from the shell 9 or the target7 until after the shell shall have already entered the lethal area. y

To the attainment of this end, Vthe video voutput of the receivermayalso be fed by conductors 104, 10S to a ringing or a poorly dampedhigh-frequency oscillating circuit 108, as shown in Fig. 16. Each videosignal, therefore,:will produce a Vtrain of oscillations, thehalf-period of which will be much less than the'width of thepulses ofVthe radio-frequency transmitter 1. As shown in Fig. 13

8 whole trains of positive and negative oscillations may thus beproduced by each video pulse, a train 51 corresponding to the echo 4, asshown in Fig. 9, and a train 52 corresponding to the echo 8. Thesetrains of oscillations may be fed by conductors 122 (Fig. 16) betweenthe screen grid 32 and the cathode 38 of another gating tube 34, inorder to lift the bias thereon provided by, say, ya biasing battery 120.

The variable-phase gating pulse output 42 of the multivibrator 29 mayalso be lfed by the conductors 101, not only between the screen grid 10and the cathode 12 of the rst gating tube 14, as previously described,but also between the control electrode 36 and the cathode 38 of thesecond gating tube 34, as shown in Fig. 16. This may be effectedsimultaneously with the application of the trains of oscillations 51 and52 to the screen grid 32. The tube 34 will therefore open up to conducteach positive oscillation for the duration of the gating pulse 42. Theoutput of the tube 34 may be inverted in any well known video amplifier53, so that a series of closely spaced positive pulses shall beavailable for application to the suppressor grid 22 of the main gatingtube 14. The delay circuit 20, of course, will be disconnected from' thesuppressor grid 22 during this mode of operation.

Since the half-period of the oscillations 51, 52 is small compared withthe width of the video signals 4 and 8, the main gating tube V14 willopen up on the application of a video signal 4 from a projectile 9 atessentially any time during the gating period of the output 42 and,therefore, at essentially any time after theY projectile 9 enters withinthe lethal area of the object 7.

The circuits and apparatus of Fig. 17 may be identical with those shownin Fig. 1, except that a supersonic transmitter 201 may V-replace theradio-locator-transmitter system 1, 6, a supersonic receiver 211 mayreplace the radio-frequency amplifier 11, `and a supersonic triggertransmitter 228 may replace the radio-frequency trigger transmitter 28.These are all shown carried by a ship 219. A depth bomb projectile 209maybe equipped with sound receivers, such 'as quartz crystals 56, thatmay be connected in similar fashion to the connections of the antennas31 and 64 of Fig. 2, and that may be connected into a cavity 233,resonant to the electric oscillations of the trigger supersonictransmitter 228,' inside a fuse mechanism 255 on or within the depthbomb. The cavity 233 may be ofthe same nature as the gas-filled,lighttransparent cavity'resonator 33 illustrated in Fig. 2.

The electric oscillations produced by the crystals 56 in response to theultrasonic waves from the transmitter 2,28, and thus'fed into the gas inthe cavity resonator 233, will ionize this gas, Vwhich will thereforebecome illuminated. The effect of the illumination is manifestedrin aphoto-cell circuit connected in series with a'batteryV When theultrasonic trigger l transmitter energizes the cavity 233, therefore,the light land an igniting charge.

produced in the cavity responsive to the ionization of the gas thereincauses current to ow in the light-sensitive photo-cell cir-cuit. lexploding' the ash-can in a manner similar to that described inconnection with theV cavity'V resonator 33 and theV photo-cell circuit,of Fig. 2. Y

Employing thisfinvention, a submarine 207wou1d not be alerted bytheexplosion'of depth-charges Yor bombsfV that might miss their mark, butwould be subjected to injury lby those depth bombs that would becomeexploded without notice when they are within lethal range ofthesubmarine. L Y p The supersonic transmitters and receivers mentionedmay, for example, be magnetostrictive or piezoelectric, according towell known technique. The supersonic pulse transmitter 201 andthesupersonic yreceiver 211, for example, may be of thevtype describedin United States Letters Patent 2,084,845, issued June 22, 1937, toEdward L. Holmes@ The ltrigger transmitter 228 may, for example, be ofany well known piezo-electric type.

This results in igniting the charge andY Other rand furthermodifications will occur to persons skilled in the art, and all such areconsidered to fall within the spirit and scope of the invention, asdefined in the appended claims.

What is claimed is:

l. An electric system having, in combination, means for detecting anexplodable object and producing a voltage signal corresponding to thesame, means for producing a voltage signal indicative of the occupationby the object of a predetermined position, and means separate from theydetecting means for thereupon in response to the said voltage signalsautomatically exploding the object during the continued detecting of theobject.

2. An electric system having, in combination, a radio locator fordetecting, producing voltage signals indicative of and indicating thetrack of objects one of which is provided with explodable means,voltage-producing means for continuously selecting along the indicatedtrack la future position of the explodable object within a preselectedrange of another of the objects, and means separate from the radiolocator and response to the voltage ofthe selecting means and to thesaid voltage signals of the radio locator for automatically energizingthe explodable means to explode the explodable object when it approacheswithin the preselected range during the continued detection by the radiolocator.

3. An electric system having, in combination, radioL locating means fordetecting, producing voltage signals indicative of and indicating thetrack of an object provided with explodable means, voltage-producingmeans for continuously selecting along the indicated track a futureposition of the explodable object, and radicecontrolled means separatefrom the radio-locating means responsive to the voltage of the selectingmeans and to the said voltage signals of the radio-locating means forautomatically energizing the explodable means to explode the object whenit reaches the future position during the continued detection by theradio-locating means.

4. An electric system having, in combination, a radiolocator system fordetecting lan object and an explodable projectile traveling towards theobject and provided with explodable means, a cathode-ray tube, means fordisplaying upon the cathode-ray tube a voltage signal received from theobject by the radio-locator system, voltageproducing means for selectingan area upon the cathoderay tube in the proximity of the object detectedby the y radio-locator system as displayed on the cathode-ray tube,

and mean-s separate from the radio-locator system responsive to the saidvoltage signal of the radio-locator system and to the voltage of theselecting means for automatically energizing the explodable means toexplode the explodable projectile when it enters the said proximityduring the continued detection by the radio-locator system.

5. In an electric system having means for propagating radio waves towardobjects in space, radio-receiving means for receiving radio waves fromboth a target in space and an explodable projectile traveling toward thetarget provided with energy-receiving means and means connected with theradio-receiving means for exploding the projectile in response to anenergy signal received by the energyreceiving means, normally ineectivemeans separate from the radio-wave propagating means for transmitting anenergy signal to the energy-receiving means, a display, means controlledin accordance with the radio waves received from both the target and theprojectile for producing indications of the distance between the targetand the projectile upon the display, means for continuously selecting-apredetermined value of distance between the target and the projectileupon the display, and means responsive to the selecting means and to thereceived radio waves and operable when the dist-ance between the targetand the projectile becomes less than the predetermined value to renderthe transmitting means effective to transmit the energy signal to theenergy-receiving means, thereby to 10 effect the explosion of theprojectile during the continued radio-wave propagation by thepropagating means.

6. In an electric system leaving means for propagating radio wavestoward objects in space, radio-receiving means for receiving radio wavesfrom both a target in space and a projectile traveling toward the targetprovided with `energy-receiving means, normally ineffective meansseparate from the radio-wave propaga-ting means for transmitting anenergy signal to the energy-receiving means, a display, means controlledin accordance with the radio waves received from both the target and theprojectile for producing indicationsofthe distance between the targetand the projectile upon the display, means for continuously selecting apredetermined value of distance between the target and the projectileupon the display, and means responsive to the selecting means and to thereceived radio waves and operable when the distance between the targetand the projectile becomes less than t-he predetermined value to renderthetransmitting means effective to transmit the energy signal to theprojectile energy-receiving means during the continued radio-wavepropaga-tion by the propagating means.

7. An electric system having, in combination, means for propagatingpulses of radio waves towards both a target and an explodable projectiletraveling toward the target provided with energy-receiving means andmeans connected with the receiving means for exploding the projectile inresponse to an energy signal received by the energy-receiving means,radio-receiving means for receiving the pulses of radio waves afterreflection and scatter from the target and the projectile, normallyinetective means separate from the radio-wave propagating means fortransmitting an energy signal to the energy-receiving means, acathode-rray-tube display, means synchronized with the propagating meansfor producing a time case upon the cathode-ray-tube display, meanscontrolled by the radio-receiving means for indicating the instants ofreception of the reccted and scattered radio waves from the target andfrom the projectile upon the time base, thereby to indicate the relativedistances or" the target and of the projectile, means for continuouslyselecting a portion of the time base corresponding to a predeterminedvalue of distance from the target, and means responsive to the selectingmeans and to the received radio waves and operable when the distancebetween the target and the projectile becomes less than thepredetermined value to render the transmitting means effective totransmit the energy signal to the energy-receiving means, thereby toeffect the explosion of the projectile during the continued radio-'wavepropagation by the propagating means.

8. An electric system having, in combination, a radiolocator system fordetecting and indicating the track of relatively movable objects one ofwhich is provided with energy-receiving means and producing voltagesindicative of the relative positions of the detected objects, meanscomprising a further voltage-producing selecting means for producing afurther voltage correlated with respect to the said voltage indicativeof another of said objects and continuously corresponding toa selectedassumed future position of the said one object within a preselectedrange of the said another of the objects, a normally inet'- fectiveelectric circuit that can be rendered eiect-ive only upon thesubstantially simultaneous application thereto of the said voltagesindicative of the said one and the said other objects detected by theradio-locator system andthe said further .voltage produced by theselecting means at the time when the said one object approaches withinthe said preselected range, means for feeding the said voltagespro-'duced by the radio-locator system and the'said further voltageproduced by the selecting means tothe normally inelfective electriccircuit, thereby automatically to render the 'electric circuit eliectiveat the said time, and means responsive to the rendering eliective of theelectric circuit for thereupon transmitting an energy 11 signal to thesaid energy-receiving means of the said one object.

9. An electric system having, in combination,Y a radiolocattor systemfor detecting and indicating the track of relatively movable objects oneof which is provided with radio-receiving means and producing voltagesindic-ative of the relative positions of the detected objects, meanscomprising a further voltage-producing selecting means for producing afurther voltage correlated with respect to the said voltage indicativeof another of the said objects and continuously corresponding to aselected assumed future position of the said one object within apreselected range of the said another of the objects, a normallyineffective electric circuit that can be rendered effective only uponthe substantially simultaneous application thereto of the said voltagesindicative of the said one and the said other objects detected by theradio-locator system and the said further voltage produced by theselecting means at the time when the said one object approaches VWithinthe said preselected range, means for feeding the said voltages producedby the radio-locator system and the said further voltage produced by theselecting means to the normally ineffective electric circuit, therebyautomatically to render lthe electric circuit effective at the saidtime, and means responsive to the rendering effective of the electriccircuit for thereupon transmitting a radio signal to the saidradio-receiving means of the said one object.

l0. An electric system having, in combination, a radiolocator system fordetecting and indicating the track of relatively movable objects one ofwhich is explodable and producing voltages indicative of the relativepositions of the detected objects, means comprising a furthervoltageproducing selecting means for producing a further voltagecorrelated With lrespect to the said voltage indicative of another ofthe said objects and continuously corresponding to a selected assumedfuture position of the said one object within a preselected'range of thesaid another of the objects, a normally ineffective electric circuitthat can be rendered eective only upon the substantially simultaneousapplication Ithereto of the said voltages indicative of the said oneIand the said other objects detected by the radio-locator system and thesaid further voltage produced by the selecting means `at the time whenthe said one object'approaches within the said preselected range, meansfor feeding the said voltages produced by the radio-locator system andthe 'said further voltage produced by the selecting means -to thenormally ineffective electric circut, Athereby automatically to renderthe electric circuit effective at the said time, and means responsive tothe rendering effective of the electric circuit for exploring the saidone object. Y

ll. An electric system having, in combination, `a rad-iolccator' systemfor detecting and indicating the track of relatively -movable'objectsone of which is provided with radio-receivingmeans and for producingvoltagesY indicative of the relative positions of the detected objects,

fective electric circuit, thereby automatically to render the electriccircuit effective at the time when the said one object approaches withinthe said preselected range, and means responsive to the renderingeifective of the electric circuit for thereupon transmitting a radiosignal to the said radio-receiving means of the said one object.

12. An electric system having, in combination, a radioenergy locator`system provided with means for propagating pulses of radio energytoward and receiving the pulses of sound energy after rellection andscatter from relatively movable objects one of which is provided withsound-energy-receiving means and means for producing pulse voltages fromthe pulses `of radio energy received from the objects, thereby toindicate the `track and measure the range of the relative positions ofthe objects, means comprising a further voltage-producing selectingmeans for producing a `further voltage correlated with respect to thesaid voltage indicative of another of the said objects land continuouslycorresponding to -a selected means comprising a furthervoltage-producing selecting means for producing a further voltagecorrelated with respect to the said voltage indicative `of another yofthe said objects and continuously corresponding to a `selected assumedfuture position of the 4said one object within a preselected range ofthe said another of the objects,

means for producing voltages rcorresponding to butV delayed from `the:said voltages'produced by the radiolocator system an interval of timecorresponding sub-. stantially to the .said p'reselectedrange, lanormally inefv feet-ive electric circuit that can be rendered effectiveonly upon the 'substantially simultaneous application thereto of thesaid voltage indicativeV of the said otherobject detected by ytheradio-locator system, the Vdelayed voltage indicative of the said oneobject and the said further voltage produced by the selecting means,means for feeding the said voltage produced by the radio-locator sys- Vtern, the said delayed voltage and the said furthervoltage produced byVthe selecting means to the normally inefassumed future position of thesaid one `object-within a preselected range of the said another of theobjects, means for producing pulse voltages corresponding to but delayedfrom the said pulse voltages produced by the radio-energy-locator systeman interval of time corresponding substantially to the said preselectedrange, a normallyV ineffective electric circuit that can be renderedeffective `only upon the substantially simultaneous application theretoof the said pulse voltage indicative of the said other object producedby the radio-energy-locator system, the delayed pulse voltage indicativeof the said `one object and the said further voltage produced by theselecting means, means for feeding -the -said pulse voltages produced bythe radio-energy-locator system, the said delayed pulse voltage and thesaid further voltage produced by the :selecting means to `the normallyineffective electric circuit, thereby to render the electric circuiteffective at the time when the said lone object approaches 'within thesaid preselected range, and means responsive yto the rendering effectiveof the electric circuit for thereupon transmitting a radio-energy signalto the said one Vobject for reception in the saidjradio-energy-receiving object, a cathode-ray tube, means for displayingupon',

the` cathode-ray tube a voltage pulse corresponding to 1a signalreceived yfrom theobject by the locato-r system, means Yfor producing agate voltage pulse of duration greaterl than that of the signal voltagepulse and for controlling the gate pulse to :select aregion upon' thecathode-ray tube corresponding to a region in the proximity of theobject, and -a transmitter responsive to the voltages of the signal iandgate voltage'pulses for K automatically `transmitting -afurther sig-nalto the projectile when it is detected by 'the locator system` as havingentered the said proximity.V

14. Anelectric system having, in combination, anrob-V ject locatorsystem provided with means for directionally transmitting energy to andreceiving energy from'an object in space and producing voltage signalsYindicative 'of the position of the object in space, means for producinga further voltage Correspon'ding to an assumed future position of theobject in space, a normallyV ineffective object signalling systemseparate from the locator system and provided with means fordirectionally transmitting .a signalwheneffective, means for causingthesignallingsystem-directional-transmitting means Vto be directed Vtovvardthe same object located by Vthe object locator 'systern, and meansresponsive to the voltage signals produced by the locator system and tothe-furthervoltage for rendering the signalling system effective at atime when the object has'entered the said assumed future position,thereby to thereupon transmit a signal to the ob- Vmeans, meansconnected with the "I3 ject during the continued object location by thelocator system. A

15. An electric system having, in combination, an object radio locatorsystem, l provided with means for dir'ectionally transmitting radioenergy to and receiving radio energy from an object in space andproducing Voltage signals indicative of the position of the object inspace, means for producing a further voltage corresponding to anassumedfuture position of the object in space, a normally ineffectiveobject radio signalling system separate from the locator system andprovided with means for directionally transmitting a radio signal wheneffective, Ymeans for causing .thesignalling-systemdirectional-transmitting means-to be directed towardthe same object located by the object locator system, and meansresponsiveto the voltage signals produced by the locator system and tothe further voltage for rendering the signalling system effective at atime when the object has entered the said assumed future position,thereby to thereupon transmit a radio signal to thel object during thecontinued object location by the locator system.

16. An electric system having, in combination, a pulseenergy locatorsystem for detecting an object in space and a projectile travelingtowards the object and producing pulse voltage signals indicative of thepositions in space of the object and the projectile, means for producinga gate voltage pulse of duration greater than that means for controllingit is detected by the locator system as having reached thev said futureposition.

17. An lelectric system having, in combination, an electromagneticpulse-energy locator system for detecting an object in space and aprojectile traveling towards the object and producing pulse voltagesignals indicative of the positions in space of the object and theprojectile, means for producing a gate voltage pulse of duration greaterthan that of the pulse voltagev signals, means for controlling the gatepulse to correlate its position with respect to the said pulse voltagesignal indicative of the position in space of thel object in order tocorrespond to an assumed future position of the projectile, and anelectromagnetic transmitter responsive to the voltages of the pulsevoltage signals and the gate pulse for automatically transmitting afurther electromagnetic signal to the projectile when it is detected bythe locator system as having reached the said future position.

1S. An electric system having, in combination, radiolocating meanslcomprising means for detecting, means for producingl voltage signalsindicative of and means for indicating the track of any object providedwith energyreceiving means, voltage-producing means for continuouslyselecting along the indicated track anfuture position of the object, andradio-controlled means ,separate from the radio-locating meansresponsive to the voltage of the selecting means and to the Vsaidvoltage signals of the radio-locating means for energizing the objectenerg receiving means when the object reaches the future position duringthe continued detection by the radiolocating means.

19. An electric system having, for detecting an object provided incombination means with energy-receiving l detecting means for producinga lvoltage signal corresponding to the object, means for producing a.voltage signal indicative of the occupation by the object of apredetermined position, and means separate from the detecting means forthereupon in response to the said voltage signals of the cccupation bythe'object of a predetermined position ener- I4 gizing the objectenergy-receiving means during the con.- tinued detecting of the object.

20. In a radio object location system in which transmitted pulses ofradio frequency energy are reecbed from a missile to be received as echopulses by said system and indicate the distance therefrom of saidmissile, the combination of means for producing pulses corresponding topulses transmitted by the said system, the produced pulses being delayedwith from said producing being activated by a coincidence betweenthe-delayed pulses and the echo pulses, control means connected to andoperated by the activation of said gating switch means for producing apredetermined signal, and means in said missile responsive to the saidsignal for detonating said missile.

21. In a radio object location system in which transmitted pulses ofradio frequency energy are reflected from a missile to be received asecho pulses by said system and indicate the distance therefrom of saidmissile, the combination of means for producing pulses delayed fromcorresponding pulses transmitted by the said system by timecorresponding to a predetermined target range, normally deactivatedgating switch means receptive of said echo pulses received by saidsystem and system for detecting at least one missile by means oftransmitted pulses of radio of time corresponding to -24. An electricsystem having, in combination, Ian energy locator for detecting objectsone of which is provided with explodable means, voltage-producing meansfor continuously selecting a future position of the explodable objectwithin a preselected range of another of the objects to be Adestroyed bythe explodable object, and means separate from the energy locatoroperable at a remote point and responsive to the voltage of theselecting means and to the energy locator for automatically energizingthe explodable means to explode the explodable object when it approacheswithin the preselected range during the continued detecting of theobjects by the Venergy locator.

25. An electric system having, in combination, energylocating means fordetecting an object provided with explodable means, voltage-producingmeans for continuously selecting a future position of the explodableobject, and energy-controlled means separate lirom the energylocatingmeans responsive to the voltage of the selecti-ng means and totheenergy-locating means for automatically energizing the explodable meansto explode the object when it reaches the future position during thecontinued detecting of the object by the energy-locating means.

26. An electric system having, in combination, energyreceiving means forreceiving energy Waves from both a target anda projectile travelingtoward the target provided with energy-receiving means, normallyineffective means for transmitting an energy signal of an entirelydifferent character than the energy waves received by the energyreceiving means to the energy receiving means, a display, meanscontrolled in accordance with the energy Waves received from both thetarget and the projectile for producing indications of the distancebetween the target and the projectile upon the display,voltage-producing means for continuously selecting a predetermined valueof distance between the target and the projectile upon the display, andmeans responsive to the voltage of the selecting means and to thereceived energy waves and operable when the distance between the targetand the projectile becomes less than the predeterminedvalue to renderthe transmitting means effective to transmit the energy signal to theprojectile energy-receiving means.

27. An electric system having, in combination, means for propagatingpulses of energy waves towards both a target and an explodableprojectile traveling toward the target provided with energy-receivingmeans and means connected with the receiving means for exploding theprojectile in response to an energy signal received by theenergy-receiving means, energy-receiving means for receiving the pulsesof energy waves after reflection and Ascatter from the target and thelprojectile, normally ineffective means separate from the propagatingmeans for transmitting an energy signal to the energy-receiving means, acathode-.ray-tube display, means synchronized with .the propagatingmeans for producing a time base `upon the cathode-ray-tubeI display,means controlled by the energy-receiving means for indicating theinstants of reception of the reflected and scattered energy waveskfromthe target and from the projectile upon the time base, thereby toindicate the relative distances' of the vtarget and of the projectile,voltage-producing means forV plodable means to explode the explodableobject when it approaches within the preselected range during thecontinued detecting of the objects by the radio locator.

29. Anv electric system having, in combination, radiolocating means fordetecting an object provided with explodable means, voltage-producingmeans for continuously selecting a future position of the explodableobject, and radio-controlled means separate from the radio-locatingmeans responsive to the voltage of the selecting means and to theVradio-locating means for automatically energizing the explodable meanswhen it reaches the future position during the continued detecting ofthe object by the radio-locating means.

30.V An electric system having, in combination, radioreceiving means forreceiving radio waves from both a target and a projectile travelingtoward the target provided withradio-receiving means, Vnormallyineffective means for transmitting a radiosignal of anventirelydifferent character than the radio waves received by the radio receiving`means to the radio receiving means, a display, means controlled inaccordance with the radio Vwaves received from both the target andtheprojectile ing means for continuously selecting a predetermined v'alueof distance between the'target and the projectile upon the display, andmeans responsive to the voltage of the selecting means and to thereceived radio waves and operable when the distance between the targetand the projectile becomes less than the predetermined value to renderthe transmitting means effective to transmit the energy signal to theprojectile energy-receiving means.

3l. An electric system having, in combination, means for propagatingpulses of radio waves towards both a target and an explodable projectiletraveling toward the target provided with radio-receiving means andmeans connected with the receiving means for exploding the projectile inresponse to a radio signal received by the Y radio-receiving means,radio-receiving means for receiving the pulses of radio waves afterreection and scatter from the target and the projectile, normallyineffective means separate fromthe propagating means for transmitting anenergysignal to the radio-receiving means, a cathode-ray-tube display,means synchronized with the propagating means'for producing a time baseupon the cathode-ray-tube display, means controlled by theradioreceiving rmeans for indicating the instants of reception of thereilected and scattered energy waves from the target and from theprojectile upon the time base, thereby to indicate the relativedistances of theV target and of the projectile, voltage-producing meansfor continuously selecting a portion of the time base corresponding to apredetermined value 'of `distance fromV the target, and

means responsiveto the voltage of the selecting means Vand to thereceived radio vwaves-and operable when the continuously selecting aportion-of the timebase corresponding to a predetermined value ofdistance from the target, and means responsiveyto the voltage of theselecting means and to the received energy-waves and operable when thedistance between the target and the projectile becomes less than thepredetermined value lto render the transmitting means effective totransmit the energy signal to the energy-receiving means, thereby toeffect the explosion of the projectile during the continued propagationand reception of the energy waves.

28. An electric system having, in combination, a radiok ,tinuously'selecting a future position of the explodable .object within apreselected range of another of theobjects to be destroyed by theexplodable object, and means seplocator for detecting objects one ofwhich is provided Y lwith explodable means, voltage-producing means forconless than the predetermined value to render the transmitting meanseffective tojtransmit the radio signal to the radio-receiving means,therebyQ to effect the explosion of the projectilefduring the continuedpropagation and reception of the radio waves.

32. An electric system having, lin combination, an energy locator fordetecting objects one of which is provided with Y signal-receivingVmeans, voltage-producing means for continuously selecting a futureposition of the said one object within a preselected range of another ofthe objects, and means operable at a point remote from the objects-andresponsive to the voltage of the selecting meansand vto Vthe locatorforautomatically sending a signal to the signal-receiving means of the,said one object when it approaches the preselectedrange. V 1.--

33. An electric system having,- inV combination, energylocating meansfor. detecting anV object provided with signal-receiving means,voltage-producing means for kcontinuously selectinga future position ofthe said object,

to explode the object and signal-controlled means responsive to lthevoltage of the selecting means and to the energy-locating means forautomatically energizing the object-signal-receiving means when theobject reaches the future position.

34. An electric system having, in combination, an energy locator fordetecting objects one of which is provided With explodable means,voltage-producing means for continuously selecting a future position ofthe eX- plodable object within a preselected range of another of theobjects to be destroyed by the explodable object, and means separatefrom the energy locator operable at a point remote from the explodableobject Iand responsive to the voltage of the selecting means and to theenergy locator for automatically causing the explodable means to explodethe explodable object when it approaches Within the preselected rangeduring the continued detecting of the object by the energy locator.

35. An electric system having, in combination, a radio locator fordetecting objects one of which is provided with explodable means,voltage-producing means for continuously selecting a future position ofthe explodable object Within a preselected range of another 'of the0bjects to be destroyed by the explodable object, and means separatefrom the radio locator operable at a point remote from the said oneobject and responsive to the voltage of the selecting means and to theradio locator for automatically causing the explodable means to eX-plode the explodable object when it approaches within the preselectedrange during the continued detecting of the objects by the radiolocator.

36. An electric system having, in combination, radiolocating means fordetecting an object provided with explodable means, voltage-producingmeans for continuously selecting a future position of the explodableobject, and radio-Wave transmitting means normally occupying one of twoconditions of energization, the radio-wave transmitting means beingseparate from the radio-locating means and responsive to the voltage ofthe selecting means and to the radio-locating means for automaticallyoccupying its other condition of energization to cause the explodablemeans to explode the object when it reaches the future position duringthe continued detecting of the object by the radio-locating means.

37. An electric system having, in combination, energylocating means fordetecting an object provided with signal-receiving means,voltage-producing means for continuously selecting a future position ofthe said object, and signal-transmitting means for signaling thesignalreceiving means and normally occupying one of two conditions ofenergization, the signal-transmitting means being responsive to thevoltage of the selecting means and to the energy-locating means forautomatically occupying the other condition of energization to producean indication at the object-signal-receiving means when the objectreaches the future position.

38. An electric system having, in combination, an energy-locator systemfor detecting relatively movable objects one of which is provided withenergy-receiving means and producing voltages indicative of the relativepositions of the detected objects, means comprising a furthervoltage-producing selecting means for producing a further voltagecorrelated with respect to the said voltage indicative of another of thesaid objects and continuously corresponding to a selected assumed futureposition of the said one object Within a preselected range of the saidanother of the objects, a normally ineffective electric circuit that canbe rendered effective only upon the substantially simultaneousapplication thereto of the said voltages indicative of the said one andthe said other objects detected by the energy-locator system and thesaid further voltage produced by the selecting means at the time whenthe said one object approaches Within the said preselected range, meansfor feeding the said voltages produced by the energy-locator system andthe said further voltage produced by the selecting means to UJI thenormally ineffective electric circuit, thereby automatically to renderthe electric circuit effective at the said time, and means responsive tothe rendering effective of the electric circuit for thereupontransmitting an energy signal to the said energy-receiving means of thesaid one object.

39. An electric system having, in combination, an energy-locator systemfor detecting relatively movable objects one of which is provided withenergy-receiving means and producing voltgges indicative of the relativepositions of the detected objects, means comprising a furthervoltage-producing selecting means for producing a further voltagecorrelated with respect to the said voltage indicative of another of thesaid objects and continuously corresponding to a selected assumed futureposition of the said one object within a preselected range of the saidanother of the objects, a normally ineffective vacuumtube gatingelectric circuit that can be rendered effective only upon thesubstantially simultaneous application thereto of the said voltagesindicative of the said one and the said other objects detected by theenergy-locator system and the said further voltage produced by theselecting means at the time when the said one object approaches withinthe said preselected range, means for feeding the said voltages producedby the energy-locator system and the said further voltage produced bythe selecting means to the normally ineffective electric circuit,thereby automatically to render the electric circuit effective at thesaid time, and means responsive to the rendering effective of theelectric circuit for thereupon transmitting an energy signal to the saidenergy-receiving means of the said one object.

40. An electric system having, in combination, an energy-locator systemfor detecting relatively movable objects one of which is explodable andproducing voltages indicative of the relative positions of the detectedobjects, means comprising a further voltage-producing selecting meansfor producing a further voltage correlated with respect to the saidvoltage indicative of another of the said objects and continuouslycorresponding to a selected assumed future position of the said oneobject within a preselected range of the said another of the objects, anormally ineffective electric circuit that can be rendered effectiveonly upon the substantially simultaneous application thereto of the saidvoltages indicative of the said one and the said other objects detectedby the energylocator system and the said further voltage produced by theselecting means at the time when the said one object approaches withinthe said preselected range, means for feeding the said voltages producedby the energy-locator system and the said further voltage produced bythe selecting means to the normally ineffective electric circuit,thereby automatically to render the electric circuit effective at thesaid time, and means responsive to the rendering eiiective of theelectric circuit for exploding the said one object.

4l. An electric system having, in combination, an energy-locator systemfor detecting relatively movable objects one of which is provided withenergy-receiving means and for producing voltages indicative of therelative positions of the detected objects, means comprising a furthervoltage-producing selecting means for producing a further voltagecorrelated with respect to the said voltage indicative of another of thesaid objects and continuously corresponding to a selected assumed futureposition of the said one object within a preselected range of the saidanother of the objects, means for producingr voltages corresponding tobut delayed from the said voltages produced by the energy-locator systeman interval of time corresponding substantially to the said preselectedrange, a normally ineffective electric circuit that can be renderedeffective only upon the substantially simultaneous application theretoof the said voltage indicative of the said other object detected by theenergylocator system, the delayed voltage indicative of the said 19 Yone object and the said further voltage produced by the selecting means,means for feeding the said voltage produced by the energy-locatorsystem, the said delayed voltage and the said further Voltage producedby the selecting means to the normally ineiective electric circuit,thereby automatically to render the electric circuit effective at thetime when the said one object approaches Within the said preselectedrange, and means responsive to the rendering effective of the electriccircuit for thereupon transmitting an energy signal to the saidenergyreceiving means of the said one object.

42. An electric system having, in combination, an energy-locator systemfor detecting relatively movable objects one of which is explodable andfor producing voltages indicative of the relative positions of thedetected objects, means comprising a further voltage-producing selectingmeans for producing a further voltage correlated with respect to thesaid voltage indicative of another of the saidobjects and continuouslycorresponding to'a selected assumed future position of the said oneobject within a preselected range of the said another of the objects,means for producing voltages corresponding to but delayed from the saidvoltages produced by the energylocator system an interval of timecorresponding substantially to the said preselected range, a normallyineffective electric circuit that can be rendered eiective only upon thesubstantially simultaneous application thereto of the said voltageindicative of the said other object detected by the energy-locatorsystem, the delayed voltage indicative of the said one object and thesaid further voltage produced by the selecting means, means for feedingthe said voltage produced by the energy-locator system, the said delayedvoltage and the said further voltage produced by the selecting means tothe normally ineiective electric circuit, thereby automatically torender the electric circuit effective at the time When the said oneobject approaches Within the said preselected range, and meansresponsive to the rendering effective of the electric circuit forthereupon exploding the said one object.

43. An electric system having, in combination, an energy-locator systemprovided with means for propagating pulses of energy toward andreceiving the pulses of energy after reilection and scatter fromrelatively movable objects one of which is provided withenergy-receiving means and means for producing pulse voltages from thepulses of energy received from the objects, thereby to measure the rangeof the relative positions of the objects, means comprising a furthervoltage-producing selecting means yfor producing a further voltagecorrelated With respect to the said voltage indicative of another of thesaid objects and continuously corresponding to a selected assumed futureposition of the said one object within a preselected range of the saidanotherof the objects, means for producing pulse voltages correspondingto but delayed from the said pulse voltages produced by theenergy-locator system an interval of time correspending substantially tothe said preselected range, a

tube, means for displaying normally ineffective electric circuit thatcan be rendered etective only upon thesubstantially simultaneousapplication thereto of the said pulse voltage indicative of the saidother object produced by the energy-locator system, the delayed pulsevoltage indicative ofthe said one lobject and the said further voltageVproduced bythe selecting means, -means for feeding the said pulsevoltages produced byv the energy-locator system, the Vsaid delayed pulsevoltage and the said `further voltage produced by the selecting meansVto the normally inetective electric circuit, thereby to render theelectric circuit effective at the time when theV said rone objectapproaches Within the said preselected range, and means responsive tothe rendering effective of the electric circuit for thereupontransmitting an energy signal lto the said one object for reception inthe saidenergy-receiving means. j

44. An electric system having, in combination, a pulse-energy locatorsystem for detecting an object and a projectile traveling towards theobject, a cathode-ray upon the cathode-ray tube a voltage pulsecorresponding to a signal received from the object by the locatorsystem, means for producing a gate voltage pulse of duration greaterthan that of the signal voltage pulse and for controlling the gate pulseto select a region upon the Vcathode-ray tube corresponding to a regionin the proximity of the object, and a transmitter responsive to thevoltages of the signal and gate voltage pulses for automaticallytransmiting a furher signal to the projecile when it is detected by thelocator system as having entered the said proximity. v

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